When working on a test upgrade; from GP2010 to GP 2015 R2. I decided to only take production company databases and left test companies, for all logical reasons. After applying GP 2010 SP4, I decided to perform a unit testing. After logging in to GP, I received following message, without having any issues later on. It was just this message:

I had a suspicion that this must be something to do with “Remember this company” option on “User and Company” window. I decided to use GP Power Tools (previously Support Debugging Tool – SDT) and SQL profiler to study this message in depth.
As suspected, results pointed to the option “Remember this company”. Now, if you remember what I said earlier, I took only the production companies for test upgrade and not the test companies. Previous consultant who was working with this client had selected a test company as his (SA’s) default company.
Now, you must also recollect that we have a SQL script to clean up missing companies’ affiliation across DYNAMICS database.
I ran the above script on the test environment and logged on to GP. This time, I was required to select a company and the message never appeared back.